There is a small, reputedly mediaeval, Jewish cemetery here in Ipswich.
Access is difficult because it is on private land, in the grounds of a
malting firm in the docks area, so I haven't been in, but it does confirm
the presence of a larger Jewish community in the past than we probably have
now. I am not aware that anyone knows where there might have been a
synagogue - today the nearest is in Colchester, though there is a tiny
Jewish section in the modern cemetery.